A second reason: "Lead RB Shonn Greene." But I digress.
A source familiar with the situation told The Tennessean's Jim Wyatt on Monday that Greene recently underwent arthroscopic surgery on his right knee and will miss the remainder of the Titans' practices until training camp opens in late July. Sources said Greene complained of soreness and developed swelling around the knee after participating in the team's recent three-day mini-camp. Doctors and trainers decided to scope the knee instead of waiting to see if it would improve on its own. It's the same knee that Greene had scoped early last season, which resulted in him missing five games.
So, for the time being, second-round rookie running back Bishop Sankey is the Titans' undisputed lead back. The Washington product was the 54th overall selection in last week's draft, the latest for a first running back to be drafted in NFL history.
The Titans are obviously looking to replace Chris Johnson, who is now with the Jets. In Sankey, the Titans have a "completely different" back, according to general manager Ruston Webster. But one back he has been compared to, via team scout, Marv Sunderland, is former Giants rusher Tiki Barber.
"He can run inside, he can run outside, he runs through guys, and he can break long runs," Sunderland told Wyatt of Sankey last week. "He has great hands out of the backfield, and he's a good blocker. He is a well-rounded back."

Fantasy Analysis:

Barber is underrated and more remembered by some for throwing his head coach and teammates under the proverbial bus late in his career. But it must be noted that he totaled at least 1,500 yards from scrimmage six times in his 10-year career and topped 2,000 yards in each of his final three seasons. He caught nearly 600 passes in his career. If the Titans can get that out of Sankey, they got a steal. Past Greene, the Titans currently have Swiss Army knife Dexter McCluster, the sluggish Jackie Battle, and special-teams ace Leon Washington at running back on their roster. Sankey may not have that second gear that CJ?K had, but he is the favorite to open the season as a starter in Tennessee's run-heavy offense.